1. Field of the Invention
The present invention pertains to the field of robotic data storage and retrieval systems that transport data storage cartridges between cartridge storage locations and cartridge drive mechanisms which conduct read, write, and erase operations on the cartridges. More specifically, the cartridge drive mechanism is provided with a cartridge shuttle mechanism that facilitates robotic transfer of the data cartridge into and out of the drive mechanism.
2. Statement of the Problem
Robotic tape library systems provide reliable, low cost data storage and retrieval services. A plurality of data cartridges, e.g., cartridges containing spooled reels of magnetic tape, reside in their respective storage compartments for use as needed. A robotic arm is used to grasp a particular cartridge for transport to a cartridge drive mechanism or drive bay that is compatible with the cartridge. The drive mechanism conducts read, write, and erase operations on the cartridge. Examples of commercially available cartridge library systems include the 4400 and Wolfcreek library systems, which can be purchased from Storage Technology Corporation of Longmont, Colo.
The robotic arms of these systems move with great speed and precision, but finite limits exist as to the tasks that the arms can perform. A robotic arm sometimes cannot be made to access a particular cartridge drive mechanism because such access requires the robotic arm to perform simultaneous tasks, or because structure on the drive mechanism interferes with travel of the arm. Thus, drive mechanisms that are designed to accommodate a manually inserted cartridge often cannot be adapted for use in robotic library systems.
FIG. 1 depicts a manual tape drive 20 that is commercially available as one of the 2000, 4000, or 6000 Series drives from Quantum Corporation of Shrewsburg, Mass. Drive 20 includes a drive bay 22 having an interior tape-receiving compartment 24. A front, manually operated handle 26 is depicted in an extended position that permits frontal access to compartment 24. Handle 26 is attached to pivot rod 28 for pivoting movement of handle 26 along arrow 30 between the extended position as depicted and a downwardly retracted position where rearward surface 32 of handle 26 abuts lower forward surface 34 beneath drive bay 22. Pivoting of handle 26 towards surface 34 provides minor positional adjustments to a data cartridge (not depicted) that is to be placed in compartment 24, latches the cartridge within compartment 24 by moving internal components within compartment 24, unlocks a tape spool (not depicted) within the cartridge, and engages the drive motor with the tape spool. As depicted in FIG. 1, pivot rod 28 has a notch 36 that can receive torque for pivoting of handle 26 through pivot rod 28.
In the commercially available device, a user operates handle 26 between the respective extended and downwardly retracted positions. Drive 20 includes a conventional solenoid lock assembly 38 that locks handle 26 into the downwardly retracted position along arrow 30 while drive 20 conducts read and write operations on the data cartridge within compartment 24. This locking feature prevents untimely attempts to remove or insert a data cartridge into compartment 24, and is controlled by conventional electronic circuits within drive 20. Thus, a user places the data storage cartridge into compartment 24, operates handle 26 to close handle 26 and cause drive 20 to load the data storage cartridge. Upon completion of the cartridge read/write operation, the user pivots handle 26 to the extended position. This motion causes the drive 20 to eject the data storage cartridge to a position where the user can manually grasp the data cartridge and remove it from compartment 24.
FIG. 2 depicts a robotic hand 40 that is commercially available from Storage Technology Corporation of Longmont, Colo., as a component in a robotic data cartridge library system. Robotic hand 40 is normally connected to the end of a conventional robotic arm (not depicted). Hand 40 includes a robotic eye 42 that scans targets for positional alignment or adjustment of hand 40. A belt-driven pulley wheel is used to extend and retract a cartridge-grasping assembly 46 between forward and rearward positions. Assembly 46 includes four outwardly extending fingers 48, 50, 52, and 54. A horizontally elongated cartridge backstop 56 is mounted in the recessed area between the respective fingers to place fingers 48 and 54 above backstop 56 while placing fingers 50 and 52 below backstop 56. A pair of opposed cartridge-grasping paddles 58 and 60 can be pivoted up and down along the direction of arrow 62 for grasping and releasing data cartridges (not depicted) that are positioned between the fingers 48-54. Paddles 58 and 60 grasp the cartridge with sufficient force to prevent the cartridge from becoming dislodged from hand 40 while hand 40 moves the cartridges from one position to another.
It has heretofore been impossible to use hand 40 (FIG. 2) for inserting a data cartridge into drive 20 (FIG. 1) and then removing the cartridge. One problem is that fingers 50 and 52 of hand 40 (FIG. 2) will contact the extended handle 26 of drive 20 (see FIG. 1) in a manner that precludes full insertion of the data cartridge into compartment 24. In the robotic cartridge insertion operation, the data cartridge must be released to compartment 24, the robotic hand moved up, and the data cartridge must be pushed in by fingers 50 and 52. Finally, the handle must be lowered to the downwardly retracted position proximal to surface 34. It is impossible to perform these operations because structure on drive 20 contacts and interferes with the required motion of robotic hand 40, e.g., as fingers 50 and 52 or paddle 58 contact handle 26. Yet another problem arises when drive 20 has finished interacting with the data cartridge. Robotic hand 40 is required to raise handle 26 to the extended position shown in FIG. 1, for ejection and removal of the data cartridge. Even if robotic hand 40 succeeds in raising handle 26, the ejected cartridge remains partial received within compartment 24 at a position that precludes paddles 58 and 60 from grasping the data cartridge. These problems prevent the use of drive 20 in a robotic library system.
There remains a true need for a device that can be used to adapt manual cartridge drive mechanisms for use in robotic systems.